bed height

I just bought, and assembled, a new CR-10. When trying to level it, I realised that the bed is too high. If I turn the screws all the way until they become loose, the bed is about .3mm below the nozzle - or too much to give accurate printing. The assembly is resting on the limit switch correctly, and the limit switch is in the right place. (I don't see how it can be wrong!).